A floating bar is a subtle way of presenting an important call-to-action to everyone who visits your page without taking up too much space.
This simple little code will work on, really, any WordPress child theme and can be set to do all kinds of different things with template functions and conditional tags. If you use MD you can expect pixel-perfection right from the start thanks to helper classes.
Sound scary? I teach you how to achieve a lot with just a little coding skills in the new MDTV series.